Oops, they did it again. Biotechnology terrorists started another scare that didn't pan out.

The U.S. Centers for Disease Control and Prevention reported that no evidence could be found that Starlink corn is causing allergic reactions in people. Starlink is a type of biotech corn not approved for human consumption that was found in Taco Bell taco shells last September.

A coalition of anti-biotech groups demanded the taco shells "be immediately removed from grocery shelves across the country." Their mouthpiece, the Genetically Engineered Food Alert, claimed the corn contained a potential allergen that could cause nausea and anaphylactic shock in some people.

Seventeen of the 28 individuals submitted blood samples to the CDC. Scientists from the U.S. Food and Drug Administration developed a test method for detecting antibodies to the Starlink corn protein, known as Cry9C. The blood tests failed to find signs of antibodies to Cry9C, indicating that none of those tested experienced allergic reactions to Starlink.

The results were not unexpected.

Concern about Cry9C stemmed from laboratory experiments reporting that the protein digests more slowly in a "simulated gastric environment" — minutes rather than seconds. Such resistance to digestion is sometimes, but not always, correlated with allergenic activity, according to food allergen experts. Cry9C is not otherwise known to be an allergen.

Experts doubted that Cry9C would be an allergen because it's not derived from a source containing any known allergens, its protein sequence does not resemble other known allergens and none of the other biotech corn proteins are allergens.

Regardless of Cry9C's allergenic potential, the protein is not likely to become an actual human allergen because humans have not been significantly exposed to Starlink corn — even allowing for the possibility of a small amount inadvertently appearing in human food.

Before an allergic reaction can occur, a person who is genetically predisposed to food allergies must consume a sufficient — not just any — amount of an allergen. During digestion, the susceptible person's body produces antibodies to the food allergen — but there is no allergic reaction upon initial exposure. It would take another subsequent exposure — at least weeks, if not months later — before enough antibodies exist to trigger an actual allergic reaction.

Sadly, none of this seems to matter to the anti-technology activists and their dupes.

The anti-biotechnology Environmental Defense Fund said the CDC sample was too small to be meaningful and that more people need to be tested.

But the CDC considered all the people that claimed to have had allergic responses. Should the CDC now engage in a wild goose chase scrutinizing millions of blood samples in search for a condition that does not exist in the most likely candidates?

One of the individuals tested, 35-year-old Grace Booth, claimed she experienced anaphylactic shock after eating an enchilada. "Frankly, I don't trust the tests ... I still feel like I haven't gotten to the bottom of this, and very much want to do that," she said.

Certainly the CDC acknowledged that it could not completely rule out the possibility that Starlink corn was associated with an allergenic response because food allergies may occur without detectable antibodies. But on the other hand, there was no evidence that the allergenic response claimed by Booth was even food-related, let alone associated with Starlink.

This is the second major biotech corn scare to wind up in the scrap heap.

In March 1999 and in August 2000, the media trumpeted alarmist results from two laboratory studies reporting "Bt" biotech corn pollen might harm Monarch butterfly larvae. Headlines such as "High-tech Corn Killing Butterflies" and "New Study Confirms Genetic Corn Kills Butterflies" appeared in newspapers around the world.

In response to the study and headlines, teams from universities and the U.S. Department of Agriculture conducted field research on Bt corn and Monarch butterflies. They reported last November that pollen levels in Bt cornfields weren't high enough to harm the Monarch caterpillars that might be feeding on milkweeds there.

The researchers found Monarch larvae actually fared better inside Bt cornfields than in natural areas, apparently because there is less pressure from predators in the cornfield. Monarchs also did much better in Bt cornfields than other cornfields because insecticides are not used in Bt cornfields.

Another important finding was that most Monarch larva development occurs before or after corn plants shed their pollen. So most Monarch caterpillars have limited exposure to pollen. Those present during pollination almost always encounter harmless doses. Purdue University's Dr. Eldon Ortman concluded that the Bt corn-Monarch butterfly scare "is not a very big issue."

The regulatory and agricultural industry gaps that inadvertently allowed a small amount of Starlink to enter the human food chain have been plugged. Biotech products will not be approved for any use unless government regulators for human consumption certify them.

Still, it would be naïve to think this is the last time anti-biotech activists start a food scare.

On the bright side, though, we should take comfort in the activists' consistency. That is, they've been consistently wrong.

Steven Milloy is the publisher of JunkScience.com, an adjunct scholar at the Cato Institute and the author of the upcoming book Junk Science Judo: Self-defense Against Health Scares and Scams (Cato Institute, 2001).